fix: do not unnecessarily force unlock

[alexandermarston]

Seeing as we know whether there is an active State Lock when we first initialise the Terraform, there isn't much point in trying to perform a force-unlock if there isn't an active lock in the first place.

This also helps scenarios where there is a stale lock ID associated with the Terraform resource, as we'll be unable to clear it. i.e:

Events:
  Type     Reason                Age                  From           Message
  ----     ------                ----                 ----           -------
  Warning  ReconciliationFailed  5m38s (x4 over 20h)  tf-controller  rpc error: code = Unknown desc = exit status 1
Failed to unlock state: failed to retrieve lock info for lock ID "ff2d104d-9560-56f7-e754-bd73005267a6": unexpected end of JSON input